Polymerization of unsaturated compounds having the cyclopentadiene nucleus



Patented Mar. 30, 1943 POLYMERIZATION F UNSATURATED COM- POUNDS HAVINGTHE CYCLOPENTADIENE NUCLEUS Samuel G. Trepp, Swarthmore, Pa., assignorto The United Gas Improvement Company, a corporation of Pennsylvania NoDrawing. Application August 9, 1938, Serial No. 223,849

Claims. *(01. 260-80) This invention pertains generally to the catalytic polymerization of unsaturated compounds such as cyclopentadieneand pertains particularly to the use of stannic chloride-organic solventcomplexes as catalysts.

The invention will be described in connection with the production ofcyclopentadiene polymer I of a specific type. However, it is to beunderstood that it may be employed in the production of polymers ofother types.

Cyclopentadiene may be polymerized into at least two broad types ofpolymers one of which is characterized by being soluble in solvents suchas benzene, toluene, chloroform, carbon tetrachloride and high flashnaphtha, while the other is characterized by being insoluble in thesesolvents.

The polymerization is usually carried out while the cyclopentadiene isin solution in a solvent.

I have discovered that the soluble type of polymer may be produced withstarmic chlorideorganic solvent complexes, and particularly stannicchloride-ether complexes, by a careful 'con trol of the polymerizingreaction.

Examples of stannic chloride complexes are stannic chloride-dimethylether complex, stannic chloride-diethyl ether complex, stannicchloridedi-isopropyl ether complex, stannic chloride-diisobutyl ethercomplex, stannic chloride-di-N- butyl ether complex, stannicchloride-methyl isopropyl ether complex, stannic chloride-ethylisopropyl ether complex, stannic chloride-methyl phenyl ether complex,stannic chloride-ethyl phenyl ether complex, stannic chloride-dioxanecomplex, stannic chloride-methyl alcohol complex, stannicchloride-acetone complex, and stannic chloride-acetic acid complex.

The preparation of complexes of this character in general comprisesadding stannic chloride to the solvent with agitation. As a result, if areaction takes place, a definite chemical compound is formed.

There are at least four factors which influence production of solublepolymer. These four factors are f 1) temperature, (2) concentration ofcyclopentadiene, (3) proportion of uniformly distributed catalyst and(4) time.

Generally speaking. and all other conditions remaining the same, itappears that there is a threshold temperature for the formation ofinsoluble polymer, and that at all temperatures below this thresholdtemperature the soluble polymer results. It is recognized, that highconcentrations of cyclopentadiene and/or high proportions of uniformlydistributed catalyst might place this theoretical threshold temperaturebelow commercially obtainable temperature levels. However, forreasonable concentrations of cyclopentadiene and reasonable proportionsof uniformly distributed catalyst a threshold temperature can be shownto exist for any given concentration of cyclopentadiene with any givenproportion of uniformly distributed catalyst.

Also generally speaking, and all other conditions remaining the same, itappears that there is a threshold concentration of cyclopentadiene forthe formation of insoluble polymer, and that at all conc ntrations belowthis threshold concentration the soluble form of polymer results. Theterm concentration of cyclopentadiene" as used herein and in the claimsspecifies the percentage by weight of total cyclopentadiene, whetherreacted or not, after all of the materials have been combined. Itis'recognized that inordinately high temperatures and/ or inordinatelyhigh proportions of uniformly distributed catalyst may make thetheoretical threshold concentration dimcult of determination. However,

for reasonable temperatures and reasonable proportions of uniformlydistributed catalyst a threshold concentration of cyclopentadiene can beshown to exist at any given temperature with any given proportion ofuniformly distributed catalyst.

Also generally speaking, and all other conditions remaining the same,and assuming that all of the materials have been combined, it appearsthat there is a threshold proportion of uniformly distributed catalystfor the formation of insoluble polymer, and that with all proportionsbelow this threshold the soluble polymer'results. In this connectionexperiments indicate quite clearly that catalyst; is apparently used upduring the polymerization of soluble polymer, and that additionalcatalyst is required to convert the soluble polymer into insolublepolymer. If the proportion of uniformly distributed catalyst is suchthat there is no catalyst available for the formation of insolublepolymer, none will be formed.

On the other hand, threshold proportions of catalyst are not required tofpolymerize all of the cyclopentadiene into the soluble polymer,although it will be recognized that a minimum proportion will berequired for maximum yields.

It is recognized that inordinately high temperatures and/or inordinatelyhigh concentrations of cyclopentadiene may make the theoreticalthreshold proportion of uniformly distributed catalyst difficult ofdetermination. However, for reasonable temperatures and reasonableconcentrations of cyclopentadiene a threshold proportion of uniformlydistributed catalyst can be shown to' exist at any given temperaturewith any given concentration of cyclopentadiene.

threshold reaction time to approach infinity. On

the other hand high temperatures, high concentrations of cyclopentadieneand/or high proportions of uniformly distributed catalyst may cause thistheoretical threshold reaction time to approach zero. However, forreasonable temperatures, for reasonable concentrations ofcyclopentadiene, and/or for reasonable proportions of uniformlydistributed catalyst. a threshold reaction time can be shown to exist.

Threshold reaction time, however, differs from the other three factorsin that when the threshold reaction time becomes more than one hour thetime necessary to form insoluble polymer approaches infinity at a veryrapid rate.

.When threshold conditions are just exceeded insoluble polymer is formedbut not exclusively. This results in a mixture of soluble and insolublepolymers. When exceeding threshold conditions to a greater extent,however, insoluble polymer is formed exclusively. The band over whichboth soluble and insoluble polymers are formed varies in width withchange in conditions. For instance. this band decreases in width withincrease in temperature.

Furthermore, the exact values of (1) tempera.- ture, (2) concentrationof cyclopentadiene, (3i proportion of uniformly distributed catalyst and(4) time at which insoluble polymer begins to appear may vary somewhatwith change in catalyst or solvent. However, the exact values may bereadily determined by test.

The soluble polymer obtained varies in physical characteristics with thesolvent used during the polymerization. For instance, solublepolycyclopentadiene obtained by polymerizing cyclopentadiene by my newprocess in solvent naphtha, toluene, or benzene differ somewhat fromeach other as shown, for example, in the suitability. of .thesepolycyclopentadienes for coating metals for which they are unusuallywell suited. As an illustration, for certain purposes the benzenepolymer is superior, the toluene polymer coming next but being,nevertheless, particularly well suited,

Accordingly, in the preparation oi my polymerized cyclopentadiene asolution of cyclopentadiene in a chosen solvent such as toluene isemployed.

I use as catalyst one or more stannic chlorideorganic solvent complexand particularly one or more stannic chloride-ether complex.

Stannic chloride itself is generally unsatisfactory, first because it ismore difficult to control and second because it fumesbadly.

The complex catalysts may be employed as; such, or in the form ofsuspensions; emulsions, or

solutions in organic solvents of which benzene, toluene, solvent naphthaand petroleum naphtha are examples. Such suspensions, emulsions, orsolutions are formed by adding the catalyst to the solvent followed bystirring. As an example, I find that a concentration of stannicchheating with the production of insoluble polymer,

or-undesirable color bodies, or both, which it is proposed to avoid.

The catalyst may be added to the solution of cyclopentadiene,particularly when the catalyst itself is in solution or in suspension ina solvent,

or the solution of cyclopentadiene may be added to a suspension,emulsion or solution of the catalyst. The reaction proceeds much moresmoothly than when the catalyst is added to the cyclopentadiene. In thelatter case no reaction appears to take place until a certain catalystconcentration is reached.

In either event, however, the addition of one material to-the other ispreferably accompanied by thorough stirring which is preferably rapid toinsure uniform distribution not only of the materials but also oftemperature.

In addition the reaction is preferably carried out in apparatus capableof temperature control such as a jacketed vessel provided with anagitator.

A very effective control of the temperature of the reaction and of localsuperheating is afforded when the preferred procedure is followed.

As an example, the proportion of catalyst may conveniently be between0.5% to 25.0% by weight of cyclopentadiene provided the temperature ofthe reaction is controlled and/or the concentration of cyclopentadieneis sufficiently low, thus avoiding the formation of insoluble polymer.

A proportion of catalyst of 10.0% by weight of the total cyclopentadienepresent is found to be portions of catalyst are employed just belowthreshold conditions. The ease with which gellike polymers are obtainedincreases with decrease in temperature. These polymers are completelysoluble.

Incidentally, the formation of gel does not indicate definitely thepresence of insoluble polymer as shown above.

'Discoloration of the product appears to increase and decrease withincrease and decrease in proportion of catalyst so that lowerproportions of catalystyield materials of lesser discoloration.

Temperatures above C. are preferably avoided and it is recommended thatgreat care be taken to keep the temperatures throughout the reactionbelow this point.-

Temperatures between -40 C. to 70 C. are suitable provided the reactantsare sufiiciently agitated or other steps taken to avoid localoverheating. The preferred temperature range is between 40 C, and 30 C.

Incidentally, it appears that the molecular weight of the resultingsoluble polycyclopentadiene may be varied somewhat by varying thetemperature.

The increase in color due to increased reaction temperature is quitenoticeable at 45 C. and becomes very pronounced as the reactiontemperature approaches 100 C.

On the other hand, at C. and even though the proportion of catalyst isfairly high, surprisingly light colored polymers are obtained.

Low reaction temperatures are, therefore, in-

dicated.

Cyclopentadiene solutions of any suitable concentration can be used,keeping in mind what has been said with respect to threshold conditions,although I more often employ concentrations of cyclopentadiene of from20 to 30% by weight of total reactants.

Incidentally, it appears that the molecular weight of the resultingsoluble polycyclopentadiene may be varied somewhat by varying theconcentration of cyclopentadiene in the starting material.

Under the recommended conditions the polymer is formed in good yield andwith a satisfactory color.

The chosen time for the reaction may vary considerably keeping in mindwhat has been said about threshold conditions. I find that for practicable purposes and good yields other conditions should be chosen suchthat the reaction time is somewhere in the neighborhood of one hour ormore. This is borne out by the fact that the yield increases withreaction time up to a certain point. The time is. of course. preferablychosen to obtain good yields.

The following specific examples will serve to further illustrate theinvention:

Example 1 2.5 grams of stannic chloride-diethyl ether complex were addedto 150 grams of toluene with agitation to form a suspension (emulsion orsolution). To this was added a mixture of 50 grams of cyclopentadieneand 50 grams of toluene during a period of minutes at a temperature of12 C. to 15 C. The mixture was stirred for 5 hours at 15 C. The catalystwas hydrolyzed with 15c. c. of an 11% sodium carbonate solution. Afteragitating for 1 hour, '75 grams of CaO was added and the agitationcontinued for an. additional period of one hour. A small quantity offilter cel was added and the mixture filtered.

The press cake was washed with toluene and the washings added to theproduct.

The resulting solution contained 40.4 grams of solublepolycyclopentadiene of 'good quality.

No insoluble polymer was obtained.

The stannic chloride-diethyl ether complex used in the foregoing examplewas made by adding 11 grams of stannic chloride to 10 grams of diethylether. The mixture was agitated in a closed flask during which heat wasevolved. All

of the stannic chloride dissolved. The solution was filtered and thecatalyst was then ready for use.

Example 2 was stirred for 5 hours at 15 C. whereupon the of extremediscoloration,

catalyst was hydrolyzed by the addition of 10 sodium carbonate. Afteragitation for one hour 50 grams of CaO was added and the agitationcontinued for an additional hour for the purpose of taking up the water.A small quantity of a filter aid was added and the mixture was filtered.The press cake was washed with toluene and the washings added to theproduct.

The resulting solution contained 29.8 grams of solublepolycyclopentadiene of good quality.

No insoluble polymer was obtained.

Generally speaking, any other stannic chlorideorganic solvent complexmight be substituted. This applies particularly to the stannicchlorideether complexes.

In the above specific examples the cyclopentadiene is in diluted formbefore addition.

The addition of water or a water solution as sive and discoloring acidconstituents of the catalyst by a suitable alkali. The alkali ispreferably added with the water used to hydrolyze the catalyst, althoughit may be added later if desired. The failure to substantiallycompletely remove the catalyst and its hydrolysis products may be thecause of serious discoloration. The insoluble reaction products formedduring the hydrolysis and neutralization remain behind on the filterleaving a highly purified filtrate. v

This polymer may be used as such, or it may be concentrated in a vacuumstill of suitable design to give a product containing any desired higherconcentration of polycyclopentadiene, including solidpolycyclopentadiene, or it might be diluted to give any desired lowerconcentration, or a second solvent might be substituted such as a higherboiling solvent. This may be done either before or after concentrationby adding the second solvent and distilling. v

In the above example the particular temperatures were chosen to controlthe physical properties such as viscosity and color of the product. Itwill be noted that at no time did the temperature exceed C. or even 70C. The manner of combining the reactants, constant agitation, and brinecooling made it possible to prevent local overheating. and the formationof .insoluble po ymer.

soluble polymer is obtained.

Carrying out the polymerization in the presence of a solvent makes itpossible to have any desired concentration of cyclopentadiene.

While in the above example no dilution of the product was required tofacilitate hydrolysis and/or filtering. it is to be understood thatdilution with a solvent may be employed, if. desired, particularly inthe case of highly yiscousproducts.

Generally speaking, for the formation of soluble polymer to theexclusion of insoluble polymer and temperatures should exceed-70 0.,concentrations of cyclopentadiene should rarely exceed 50% by weight ofthe total solution except possibly at low temperatures, andconcentrations of uniformly distributed catalyst should rarely exceed25% by weight of cyclopentadiene.

It should be kept in mind'that there are for practical purposes minimumvalues for temperature, concentration of cyclopentadiene, proportion ofcatalyst and time, which practice will show stood that any other solventmay be substituted of which benzene, xylene, ethyl benzene. solventnaphtha, petroleum naphtha, carbon tetrachloride, and ethylenedichloride are especially suitable.. The products with benzene andtoluene are preferred for specific uses ashereinafter referred Althoughin the above particular description the cyclopentadiene is dilutedbefore the addition of the catalyst. it is to be understood thatvariations are possible. For instance, it is conceivable that all of thediluent may be first mixed with one of the reactants (either catalyst orunsaturated compound) and that the other reactant may be added inconcentrated form, particularly if the principles set forth herein areclosely observed. Or the larger part of the diluent may be added to oneof the reactants so that the other is relatively concentrated. It isalso conceivable that, with the exercise of extreme care and the closestadherence to the principles set forth herein, both reactants mightpossibly be employed in relatively concentrated form. Other variationsare possible. When adding one liquid to another with agitation I find itconvenient and often preferably to do this below the surface of one ofthe liquids. 1 ;Any other suitable alkali such as sodium hydroxide,sodium carbonate, sodium bicarbonate,

magnesium hydroxide, an amine or other basic substance might besubstituted for quicklime in the above specific examples, followed by anonacidic drying agent such as N82SO4, or soda lime. Both neutralizationand drying is effected by CaO.

In case it is desired to form a highly concentrated solution ofpolycyclopentadiene or to isolate it in solid form, it is not necessaryto dry the solution after neutralization as the water present can bereadily removed in the subsequent concentrating operation. The completeremoval of insoluble material present, such as the neutralizing agent,is then effected by filtering the partially concentrated solution afterthe complete removal of the water present by distillation. After thisstep the solution can be further concentrated if desired.

The product may be used for many purposes, for instance, for lacquersgenerally, for varnishes either alone or in admixture with other resins,for enamels, for paints, or in fact for coating compositions generally.It is ideally suited to the coating of metals, for instance, for thecoating of 2,314,911 rarely exceed 100 C., andpreferably should not foodcontainers as described and claimed in copending application, SerialNumber 291,007, filed August 19, 1939, by Newcomb K. Chaney. This isespecially true of the products polymerized in benzene and toluene.

If desired, it is possible to obtain soluble. polycyclopentadiene ofhigher viscosity or of otherwise changed characteristics by starting'with a solution of polycyclopentadiene and stopping the reaction beforethreshold conditions are exceeded.

While the invention has been particularly described inconnection withthe polymerization of cyclopentadiene, it is.to be understood that it isapplicable to the polymerization of substituted cyclopentadienes havingthe cyclopentadiene nucleus containing the characteristic conjugateddouble bonds. However, it is to be understood that the polymerparticularly described has certain unique characteristics whichdistinguish it from polymers prepared from other starting materials.Examples of such other compounds are the aIkyL-aryl, and alkyl-aryl.

It is to be understood that the above specific examples are by way ofillustration. Therefore, changes, omissions, additions, substitutions.

' and/or modifications might be made within the drolyzable complex;

scope of the claims without departing from the spirit of the inventionwhich is intended to be limited only as required by the prior art.

I claim:

1. A process for producing benzene-soluble cyclic diene polymer by thecatalytic polymerization of a cyclic diene compound selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene in the substantialabsence of polymerizable compounds not con-',

tained in said class, comprising mixing with said cyclic diene in thepresence of a solvent to effect said polymerization in considerableproportion to said cyclic diene polymer a hydroly'zable stannicchloride-organic solvent complex previously formed by reacting stannicchloride with an organic solvent capable of reacting with stannicchloride to form said hydrolyzable complex; and preventing thepolymerization of said cyclic diene from being effected entirely tobenzene-insoluble cyclic diene polymer by thoroughly agitating thereaction mass while maintaining the reaction temperature below 0., theconcentration of said cyclic diene below 50% by weight, and theproportion of catalyst to said cyclic diene below 25% by weight, and bystopping the reaction by inactivating said catalyst whilebenzene-soluble cyclic diene polymer is present in the reaction mass.

2. A process for producing benzene-soluble cyclic diene polymer by thecatalytic polymerization. of a cyclic diene compound. selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene in the substantialabsence of polymerizable compounds not contained in said class,comprising mixing with said cyclic diene in the presence of a solvent toeffect said polymerization inconsiderable proportion to said cyclicdiene polymer a hydrolyzable stannic chloride-organic solvent complex.previously formed by reacting stannic chloride with an organic solventcapable of reacting with stannic chloride to form said hyand preventingthe polymerization of said cyclic diene from being effected largely tobenzene-insoluble cyclic diene polymer by thoroughly agitating thereaction polycyclopentadiene by the catalytic polymerization ofcyclopentadiene in the substantial aosence of polymerizable compoundsother than cyclic dienes selected from the class or cyclic dienesconsisting of cyclopentadiene, allgvl substituted cyclopentadiene andaryl substituted cyclopentadiene, comprising mixing with saidcyclopentadiene in the presence of a solvent to enact saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable stannlc chloride-organic solvent complex previously iormedby reacting stannic chloride with an organic solvent capable of reactingwith stannic cnloride to Iorm said hydrolyzab'le complex; and

preventing the polymerization of said cyclopentadiene from beingeiiected entirely to benzeneinsoluble polycyclopentadiene by thoroughlyagitating the reaction mass while maintaining the reaction temperaturebelow 70 0., the concentration of said cyclopentadiene below 50% byweight, and the proportion of catalyst to said cyclopentadiene below byweight, and by stopping the reaction by inactivating said catalyst whilebenzene soluble polycyclopemadiene is present in the reaction mass.

4. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof polymerizable compounds other than cyclic dienes selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene, comprising mixingwith said cyclopentadiene in the presence of a solvent to effect saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable stannic chloride organic solvent complex previously formedby reacting stannic chloride with an organic solvent capable of reactingwith stannic chloride to form said hydrolyzable complex; and preventingthe polymerization of said cyclopentadiene from being eflected largelyto benzene-insoluble polycyclopentadiene by thoroughly agitating thereaction mass while maintaining the reaction temperature below 70 0.,the concentration of said cyclopentadiene below 50% by weight, and theproportion of catalyst to said cyclopentadiene below 10% by weight, andby stopping the reaction by inactivating said catalyst whilebenzene-soluble polycyclopentadiene is the preponderant polymer presentin the reaction mass.

5. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene inthe substantial absence ofpolymerizable compounds other than cyclic dienes selected from the classof cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene, and aryl substituted cyclopentadiene, comprising withsaid cyclopentadiene in the presence of a solvent to effect saidpolymerization in considerable proportion to poly'cyclopentadiene ahydrolyzable stannic chloride-organic solvent complex previously formedby reacting stannic chloride with an organic solvent capable of reactingwith stannic chloride to form said hydrolyzable complex; andsubstantially completely preventing the conversion' of saidcyclopentadiene to benzene-insolu-.

ble polycyclopentadiene by thoroughly agitating the reaction mass whilemaintaining the reaction temperature below 70 C., the concentrationcomprising diluting said cyclopentadiene with asuitable solvent,diluting with a suitable solvent a hydrolyzable stannic chloride-organicsolvent complex previously formed by reacting stannic chloride with anorganic solvent capable or reacting With stannic chloride to form saidhydrolyzable complex, enacting said polymerization in considerableproportion to polycyclopentadlene by slowly adding said solution orcyclopentadiene to said diluted catalyst with thorough mixing whilemaintaining the reaction temperature below 10 C., the concentration ofsaid cyclopentadiene below 50% by weight, and the proportion or catalystto said cyclopentadlene below 10% by weight, and stopping the reactionby inactivating said catalyst belore substantially any benzenelnsolublepolycyclopentadiene is present in the reaction mass.

7-. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentad ene in the substantial absenceof polymerizable compounds other than cyclic dlenes selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene, comprising mixingwith said cyclopentadiene in the presence of a solvent to efiect saidvcyclopentadiene is the prepolicierant polymer present in the reactionmass.

8. A process tor producing benzene-soluble polycyclopentadiene by the caalytic polymerization or cyclopentadiene in the substantial absence oiall other compounds polymerizable'under tne conditions obtaining;com-prising mixing with said cyclopentadiene in the presence of asolvent to effect said polymerization in considerable proportion topolycyclopentadiene a hydrolyzable stannic chloride-organic solventcomplex previously formed by reacting stannic chloride with an organicsolvent capable of reacting with stannic chloride to form saidhydrolyzable complex; and

preventing the polymerization 01' said cyclopentadiene from beingeflected entirely to benzene-insoluble polycyclopentadiene by thoroughlyagitating the reaction mass while maintaining the reaction temperaturebelow 100 C., the concen-' tration of said cyclopentadiene below 50% byweight, and the proportion of catalyst to said cyclopentadiene below 25%by weight, and by stopping the reaction by inactivating said catalystwhile benzene-soluble polycyclopentadiene is present in the reactionmass.

9. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceor all other compounds polymerizable under the conditions obtaining,comprising mixing with said cyclopentadiene in the presence of a solventto effect said polymerization in considerable proportion topolycyclopentadiene a hydrolyzable stannic chloride-organic solventcomplex previ-' ously formed by reacting stannic chloride with anorganic solvent capable of reacting with stannic chlroide to form saidhydrolyzable complex;

and preventing the polymerization of said cyclopentadiene frombeing'eflected largely to benzene-insoluble polycyclopentadiene bythoroughly agitating the reaction mass while maintaining the reactiontemperature below 45? C., the concentration of said cyclopentadienebelow 50% by weight, and the proportion of catalyst to saidcyclopentadiene below 10% by weight, and by stannic chloride-organicsolvent complex previously formed by reacting stannic chloride with anorganic solvent capable oi reacting with stannic chloride to form saidhydrolyzable complex; and preventing the polymerization of saidcyclopentadiene from being effected largely to benzene-insolublepolycyclop'ontadiene by thoroughly agitating the reaction ihass whilemaintaining the reaction temperature below C.; the concentration of saidcyclopentadiene below by weight, andthe proportion of catalyst tosaidcyclopentadiene below 10% by weight, and by stopping the; reactionby inactivating said catalyst while benzene-soluble polycyclopentadieneis the preponderant polymer present in the reaction H1885.

SAMUEL G. TREPP.

